#define _CRT_SECURE_NO_WARNINGS 1
#include<assert.h>
#include<stdio.h>

//int my_strlen(const char* arr) {
//	assert(arr !=  'null');
//	int len = 0;
//	while (*arr++) {
//		len++;
//	}
//	return len;
//}
//int main() {
//	char arr[] = "abcdef";
//	my_strlen(arr);
//	printf("%d\n", my_strlen(arr));
//	return 0;
//}

char* my_strcpy(char* destination, const char* source) {
	assert(destination && source);
	char* temp = destination;
	while (*destination++ = *source++) {
		;
	}
	return temp;
}
int main() {
	char arr1[] = "hello world";
	char arr2[20] = { 0 };
	printf("%s\n", my_strcpy(arr2, arr1));
	return 0;
}